The invention relates to a process for the preparation of methyl tertiary butyl ether (MTBE) by contacting an isobutene-containing hydrocarbon flow, predominantly consisting of hydrocarbons with 4 carbon atoms, with methanol in a reaction zone in the presence of a catalyst and separating the methyl tertiary butyl ether formed from the reaction mixture.
It is known to react isobutene with methanol in the presence of an acid catalyst, yielding methyl tertiary butyl ether (MTBE), for instance as described in U.S. Pat. Nos. 2,480,940 and 3,037,052. The isobutene is mostly applied in the form of C.sub.4 -raffinate 1, originating from the thermal or catalytic cracking of hydrocarbons. Besides isobutene, this C.sub.4 -raffinate 1 also contains monoalkenes and saturated hydrocarbons as well as possibly small amounts of acetylenic and dialkenic hydrocarbons, but almost no butadiene.
After the isobutene present in this C.sub.4 -raffinate has been reacted with methanol in the presence of a catalyst in a reaction zone, yielding MTBE, the MTBE formed is separated and the remaining C.sub.4 -hydrocarbon flow, also called the C.sub.4 -raffinate 2 and consisting mainly of n-butene and butanes, is discharged. The value of this C.sub.4 -raffinate 2 generally does not exceed its calorific value.